IPv6 multipath static routes with different weights and BFD supervision

Μιχαήλ Κωτσιούρος michailkots at hotmail.com
Tue Jan 23 15:56:22 CET 2018

Hi Ondrej,
thanks a lot for the clarification and your quick response!!!

Best Regards
Michail Kotsiouros
From: Ondrej Zajicek <santiago at crfreenet.org>
Sent: Tuesday, January 23, 2018 4:36 PM
To: ?????? ??????????
Cc: bird-users at network.cz
Subject: Re: IPv6 multipath static routes with different weights and BFD supervision

On Mon, Jan 22, 2018 at 03:39:06PM +0000, ?????? ?????????? wrote:
> Hi BIRD experts,
> I face some problems on static routes on IPv6. I try to configure multipath static routes that are supervised with BFD. I use the following conf:
> route <DEST_IPv6> multipath
>         via <NEXT_HOP1_IPv6> weight 10 bfd
>         via <NEXT_HOP2_IPv6> weight 20 bfd;
> This does not seem to have the expected behavior since I notice that the static routes are configured with the same priority rather than having the less weighted one with higher priority than the more weighted.
> When I try to check the routes passed to the kernel I notice this:
> <DEST_IPv6> via <NEXT_HOP1_IPv6> dev eth3  proto bird  metric 1024
> <DEST_IPv6> via <NEXT_HOP2_IPv6> dev eth5  proto bird  metric 1024
> The same configuration for IPv4 works as expected...
> could you, please, give me some initial orientation regarding the issue?


I think that older kernels (ones that report IPv6 ECMP routes as multiple
routes) do not support weight for IPv6. On Jessie, i cannot set IPv6
weighted ECMP even using 'ip route add'.

Not sure about newer kernels. BIRD uses older IPv6-ECMP API for route
changes (to be compatible with older kernels), so we do not support
weight here neither.

Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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